"+1 Bonus Spin Point for Pai's Machine of Wonders each month you have premium activated, spin points do not expire!"

Does this imply that if you have like, 3 points for say, July, and don't pay for premium in August, but pay again in September, will you still have 3 points or do they expire because premium wasn't paid a month in? Do points also stack up by the way, or is it just one point and that's it?